The winding of convolute paper tubes in lengths up to about 200" has been practiced routinely for many years. One form of such convolute winding is disclosed in U.S. Pat. No. 3,073,218, which uses means for drawing a strip of paper from a roll, applying an adhesive to the paper, cutting it to the desired length of the tube to be formed, moving the cut length or sheet of paper longitudinally into engagement with a longitudinally extending groove in one side of an elongated mandrel of a length greater than the cut paper sheet, rotating the mandrel to wind the paper sheet thereon in convolute form, and then stripping the tube from the mandrel by a stripper blade moving longitudinally thereof as the next sheet of paper moves into engagement with the mandrel groove.
In the apparatus of the above-mentioned patent, the longitudinal movements of both the paper sheet and the wound tube are derived from a significantly heavy carriage supported on rollers and connected to a chain drive for reciprocation thereby. The reciprocating carriage includes complicated apparatus for plunging sharp pins through the sheet of paper from the underside thereof and near the edge thereof which is to engage the groove in the mandrel. Longitudinal movement of the carriage while the pins are in penetrating relation with the sheet of paper pulls the paper longitudinally of the mandrel until fully engaged in the longitudinal groove therein. The pins are then withdrawn from the paper sheet, leaving it in position to be wound up on the mandrel, while the reciprocating carriage moves in return direction to pick up another sheet of paper.
The reciprocating carriage is necessarily very heavy, about 500 pounds, due to the penetrating pin apparatus included therein, even though the penetrating pins are disposed only near one edge of the sheet of paper in order to keep the weight low and the mechanisms within reason. The heavy carriage requires a heavy drive apparatus, and the reciprocation of the heavy carriage is noisy and results in severe stress with attendant high maintenance and downtime both for the reciprocating apparatus and for the penetrating pin apparatus. Also, as the penetrating pins must accelerate and move the paper sheet along by force applied to the one edge thereof, there is a tendency for the paper to wrinkle and skew, causing misalignment with the mandrel and resultant poor quality tube winding. Pin penetration of, and pulling against, the paper may cause physical damage to the paper and poor quality tubes.
Therefore, it is an object of the present invention to eliminate the heavy reciprocating carriage with its attendant problems, and to provide a means for advancing the paper sheet smoothly into full engagement with the longitudinal groove in the mandrel by carrying the paper sheet on conveyor belts which are frictionally engaged with the paper and are slidable relative to the paper during the acceleration and deceleration of the paper sheet as it is picked up after cutting and then halted in suitable position for winding into a convolute tube. As the conveyor belts engage and support the paper sheet generally across its full width and engage by friction alone, there is less tendency to wrinkle, skew, or misalign the paper, the conveyor belts may be run continuously, without intermittent or reciprocating motion, and the apparatus may be run at a higher cyclic rate in some cases because there is no problem with a heavy reciprocating carriage. The simplicity of the conveyor belts and omission of the penetrating pins eliminate many problems as to maintenance, as well as the higher initial cost of the reciprocating and penetrating pin apparatus and the higher cost for more complicated parts for maintenance.